Tag: golang

An array is a data structure that consists of a collection of elements of a single type or simply you can say a special variable, which can hold more than one value at a time. The values an array holds are called its elements or items. An array holds a specific number of elements, and it cannot grow or shrink. Different data types can be handled as elements in arrays such as Int, String, Boolean, and others. The index of the first element of any dimension of an array is 0, the index of the second element of any array dimension is 1, and so on.

import "fmt"

func main() {
    // declare an array
    var colors [3]string
    // assign values to array
    colors[0] = "Red"
    colors[1] = "Green"
    colors[2] = "Blue"
    
    // print all items in array
    fmt.Println(colors)
    // print on item of an array
    fmt.Println(colors[1])
    
    // declare and assign
    var numbers = [5]int{5, 4, 2, 1, 10}
    fmt.Println(numbers)
    
    // print length of array
    fmt.Println("Number of colors:", len(colors))
    fmt.Println("Number of numbers:", len(numbers))
}

Initialize an Array with an Array Literal

x := [5]int{10, 20, 30, 40, 50}   // Intialized with values
    var y [5]int = [5]int{10, 20, 30} // Partial assignment

 

References
https://www.golangprograms.com/go-language/arrays.html

import (
    "fmt"
)

func main() {
    var p *int
    var v int = 42

    // put memory address of v in p
    p = &v

    // print memory address of v
    fmt.Println(p)

    // print value of v
    fmt.Println(*p)

    // change value of v by changing pointer value
    *p = 50

    // print value of p
    fmt.Println(v)
}

 

import "fmt"

func main() {

    var str string
    fmt.Print("Enter a string: ")
    // scans text read from standard input, storing them space-separated
    // for example we can read Mahmood from input, but not Mahmood Ramzani
    fmt.Scanln(&str)
    fmt.Printf("String Value : %v\n",str)

    var str1,str2 string
    fmt.Print("Enter two string: ")
    fmt.Scanln(&str1,&str2)
    fmt.Printf("String Value1 : %v\n",str1)
    fmt.Printf("String Value1 : %v\n",str2)
}

import (
    "bufio"
    "fmt"
    "os"
    "strconv"
    "strings"
)

func main() {

    reader := bufio.NewReader(os.Stdin)
    fmt.Print("Enter text :")
    str, _ := reader.ReadString('\n')
    fmt.Println(str)

    fmt.Print("Enter a number : ")
    str, _ = reader.ReadString('\n')
    // trim space
    trimmedStr := strings.TrimSpace(str)
    // convert string to int
    number, err := strconv.ParseInt(trimmedStr, 10, 32)

    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(number)
    }
}

 

import "fmt"

func main() {

    // using the default formats
    fmt.Println("Hello Mahmood")

    // return values from Println
    n, _ := fmt.Println("Hello Mahmood 2")

    // formats according to a format specifier
    fmt.Printf("Length : %d\n", n)

    isTrue := true
    aNumber := 1400
    name := "Mahmood"

    // The verbs:

    // values in a default format
    fmt.Printf("Boolean : %v\n", isTrue)
    fmt.Printf("Number : %v\n", aNumber)
    fmt.Printf("String : %v\n", name)

    // values with specified format
    fmt.Printf("Boolean : %t\n", isTrue)
    fmt.Printf("Number : %d\n", aNumber)
    fmt.Printf("String : %s\n", name)

    // formats according to a format specifier and returns the resulting string
    myString := fmt.Sprintf("Hello %s", name)
    fmt.Println(myString)
}

References
https://golang.org/pkg/fmt/

package main

import (
    "fmt"
    "time"
)

func main() {

    i := 2
    fmt.Print("Write ", i, " as ")
    switch i {
    case 1:
        fmt.Println("one")
    case 2:
        fmt.Println("two")
    case 3:
        fmt.Println("three")
    }

    switch time.Now().Weekday() {
    case time.Saturday, time.Sunday:
        fmt.Println("It's the weekend")
    default:
        fmt.Println("It's a weekday")
    }

    t := time.Now()
    switch {
    case t.Hour() < 12:
        fmt.Println("It's before noon")
    default:
        fmt.Println("It's after noon")
    }

    whatAmI := func(i interface{}) {
        switch t := i.(type) {
        case bool:
            fmt.Println("I'm a bool")
        case int:
            fmt.Println("I'm an int")
        default:
            fmt.Printf("Don't know type %T\n", t)
        }
    }
    whatAmI(true)
    whatAmI(1)
    whatAmI("hey")
}

References
https://gobyexample.com/switch

package main

import "fmt"

func main() {

    if 7%2 == 0 {
        fmt.Println("7 is even")
    } else {
        fmt.Println("7 is odd")
    }

    if 8%4 == 0 {
        fmt.Println("8 is divisible by 4")
    }

    if num := 9; num < 0 {
        fmt.Println(num, "is negative")
    } else if num < 10 {
        fmt.Println(num, "has 1 digit")
    } else {
        fmt.Println(num, "has multiple digits")
    }
}

References
https://gobyexample.com/if-else

package main

import "fmt"

func main() {

    i := 1
    for i <= 3 {
        fmt.Println(i)
        i = i + 1
    }

    for j := 7; j <= 9; j++ {
        fmt.Println(j)
    }

    for {
        fmt.Println("loop")
        break
    }

    for n := 0; n <= 5; n++ {
        if n%2 == 0 {
            continue
        }
        fmt.Println(n)
    }
}

References
https://gobyexample.com/for

package main

import (
    "fmt"
    "math"
)

const s string = "constant"

func main() {
    fmt.Println(s)

    const n = 500000000

    const d = 3e20 / n
    fmt.Println(d)

    fmt.Println(int64(d))

    fmt.Println(math.Sin(n))
}

References
https://gobyexample.com/constants

package main

import "fmt"

func main() {

    var a = "initial"
    fmt.Println(a)

    var b, c int = 1, 2
    fmt.Println(b, c)

    var d = true
    fmt.Println(d)

    var e int
    fmt.Println(e)

    f := "apple"
    fmt.Println(f)
}

References
https://gobyexample.com/variables

Create GOPATH folder
Create a folder in your project directory.This folder is going to be your GOPATH folder.
I creeated a folder named go for my specific GOPATH inside my project.

cd go
mkdir src

Create project folder

cd src
mkdir msync # project folder

Setup Jetbrains Gogland IDE

set the IDE to use your specific GOPATH not the global GOPATH

go get

every time you want to get an external package open a terminal ( I have tested in Linux) :

GOPATH=~/git/mediasync/go/

go env # for checking env

go get github.com/eclipse/paho.mqtt.golang

References
https://www.jetbrains.com/help/go/getting-started-with-gogland.html
https://stackoverflow.com/questions/37163048/how-to-install-github-repository-in-a-specific-gopath